Jpn. J. Pharmacol. 74 (1), 113-115 (1997)

Acetylcholine-Induced Relaxation of Rat Aorta Is Greatest during Estrus in the Sexual Cycle

Hideo Honda, Hisayuki Ishihara, Mai Takei and Hiroshi Kogo

Department of Pharmacology, Tokyo University of Pharmacy and Life Science, 1432-1, Horinouchi, Hachioji, Tokyo 193-03, Japan

Abstract: Acetylcholine (ACh)-induced relaxation in the aortae precontracted with norepinephrine was significantly enhanced in the aortae from estrus (E) rats, compared with that in those from metestrus (D-1), diestrus (D-2) and proestrus (PE) rats. NG-Nitro-L-arginine methyl ester (L-NAME) inhibited the endothelium-dependent relaxation in E rats. These results suggest that there is a difference in ACh-induced relaxation of the thoracic aorta during the sexual cycle of rats, and the relaxation is greatest in E of the sexual cycle; this may be due to a difference in nitric oxide synthesis in the endothelium in the sexual cycle.

Keywords: Sexual cycle, Nitric oxide, Aorta

Copyrightę The Japanese Pharmacological Society 1997

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